Surge arrester for air lines



y 1951 N. 0. H. SlDENMARK SURGE ARRESTER FOR AIR LINES Filed May 4, 1949 IN EN R N L L H BLNBR ENMi-BR r a AT TORNEYS Patented July 10, 1951 SURGE ARRESTER FOR AIR LINES Nils Olof Hjalmar Sidenmark, Danderyd, Sweden, assignor to Telefcnaktiebolaget L. M. Ericsson, Stockholm; Sweden, a -company of Sweden Application May 4, 1949, Serial No. 91,401

In Sweden May 21, 1948 I'Glaim. l

The present invention relates to a surge arrester for air lines, especially telephone lines. It is known, that owing to atmospheric disturbances high tensions can arise on such lines. Many measures have been proposed to neutralize these tensions. According to the U. S. Patent Application 640,601, now Patent No. 2,535,423, the tie wire used for fastening of the line on the insulator is bent in a suitable manner against the earthed (or anyway not insulated from earth) iron bracket, so that an air gap having a suitable width arises between the wire and the bracket. The air gap must be such that it is possible for a light are for excess voltage to bridge over it, but it must be so great and placed so, that it will not be filled with water, snow, etc., which would cause a leakage to earth of the ordinary currents. The known device has however certain draw-backs. The tie wire cannot be chosen so thick, as would be suitable in order to obtain a wire sufliciently stiff to fix the air gap properly. Surthermore the wire acquires a certain tendency to wind up due to the winding of the tie wire round the line wire, whereby the position of the part bent down towards the bracket is changed, and therewith the position and size of the air gap.

In an arrangement according to the invention these draw-backs are avoided the protecting wire being mechanically connected to and kept in r position by the lower edge of the insulator.

The invention will be described more closely with reference to the accompanying drawing, in which Figs. 1, 2 and 3 show different embodiments of a device according to the invention.

In Fig. 1, an insulator l is shown, fastened on a metal bracket or insulator pin 2. A telephone wire 3 is lashed to the insulator by means of a lashing 4. A protecting wire 5 is wound round the line 3 at a certain distance from the lashing and drawn down towards the lower edge ll of the insulator, round which it is bent with a bending 6 so that it is kept in position by the insulator. The protecting wire thereafter continues down towards the insulating pin 2 so that an air gap 9 is formed between a flange 8 or the pin 2 and the protecting wire. It can naturally also be supposed, that the protecting wire could be bent so that an air gap would arise from the protecting wire to a bracket, on which the insulator pin is fastened. The main thing is that the air gap can arise between the protecting wire and an earthed part or at least a part which is not directly insulated from earth.

The device shown in Fig. 2 differs from the device in Fig. 1 only in that the protecting wire is not itself bent round the edge I of the insulator, but a special sleeve clutch IE3 has been placed on the protecting wire. Said clutch l0, suitably made of brass or the like, is shaped to form a sleeve provided with a strip which can be bent round the lower edge 1 of the insulator, thus forming a bending B.

In the device shown in Fig. 3 the sleeve clutch i0 is simultaneously shaped as a jointing sleeve, so that the protecting wire 5 consists of two portions, one fastened to the line 3, and one stretching from the clutch ID to the air gap 9.

The different embodiments shown in Figs. 1, 2 and 3 present difierent advantages. Thus, the embodiment shown in Fig. 1 has the advantage, that it can be made directly on the spot with available material. The wire 5 must in this case be so soft, and have such a small thickness, that the bending 5 can be made without damaging the insulator and using special tools.

In the embodiment shown in Fig. 2 a special sleeve clutch I0 is used, which makes the mounting quicker and more convenient. This sleeve clutch is provided with such a bending 6, that it fits to most of the insulators occurring in the practice. If a sleeve tube is used to connect the protecting wire 5 with the line 3 instead of the protecting wire being wound round the line as shown in the drawing, the wire 5 can be made of a thicker and harder material.

The embodiment shown in Fig. 3 is especially suitable for such lines, in which the conductor is of a soft and relatively fusible material as aluminum. The part of the protecting wire 5 connected to the conductor is suitably made of the same material as the conductor. This is necessary in aluminum conductors to avoid corrosion. The sleeve clutch Ill is in this case shaped as a jointing sleeve, so that the lower part of the protecting wire close to the air gap 9 consists of a special wire which can be made of a material with high fusing point to prevent it from being worn away by a light are over the air gap. The usual tie wire 4 used for fastening the line 3 to the insulator I can also be used as protecting wire according to the invention. The tie wire is then wound on the conductor until a suitable distance from the insulator, whereafter is is lead down according to what has been described above.

Due to the protecting wire resting against the insulator, one of the greatest advantages with a device according to the invention consists of the air gap being fixed as regards the length.

It is very important, since the practice has shown, that the length ought not to surpass 7 mm.

I claim:

For use with an insulator support having a metal part, a skirted insulator thereon and an overhead line Wire attached to the insulator above the skirt, a surge arrester comprising a rigid conductor including a first wire of the same metal as and for attachment to an overhead line and formed to extend alongside of an insulator, a second wire for connection to said conductor and having a gap forming end made of suitable hard metal and extending into such proximity to a metal insulator-supporting part as to form a short air gap and a joining metal sleeve securing said first and second Wires together, said sleeve having an integral hook-like extension for engaging under the lower edge of the insu- 4 lator skirt to fix the conductor thereto to maintain the gap size.

NILS OLOF HJALMAR SIDENMARK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 949,130 Rheinberger Feb. 15, 1910 1,147,021 Hickey July 20, 1915 2,392,342 Steinmayer Jan. 8, 1946 FOREIGN PATENTS Number Country Date 605,171 Great Britain July 16, 1948 

